Brendan's post on cantrips reminded me of some stuff I'd done with them, but also raised a side question: the damage limit of a cantrip. You see, a 1st level spell, if it does damage, is somewhere in the 1d6 range. A cantrip should thus do less damage, or if it does a d6 for damage, there should be some other limit to it, to keep it in the 0-level spell range. Efforts to create ultra-low-level damage spells seem like power creep, especially since there's usually no attack roll and it's harder to "disarm" an M-U than a thief or fighter (unless the M-U is using cantrip scrolls or wands.) If there's a saving throw, a cantrip suddenly becomes more likely to hit than a thrown dagger.
My thought is to make attack cantrips fit a simple template: standard attack roll, 1 point of damage, has one additional effect on a 5+ roll (on 1d6). It's no more difficult to roll this than a mundane attack, and we can vary the additional effect to create a variety of cantrips:
Bolts of Bedevilment: knocks target backwards.
Sorcerer's Sting: pain causes target to drop objects in hand.
Enchanted Embers: can set beard or clothing on fire (extra point of damage unless put out.)
Necromantic Numbness: deadens nerves (-1 on actions for 3 rounds.)
Dazzling Dagger: shower of sparks blinds for 3 rounds.
As a bonus, here's a link to the updated "Cantrips Gone Wild!" article that I wrote for Fight On! #13. You can use the rules there for cantrip scrolls or wands with these attack cantrips. A 1st level Magic-User with a Staff of Cantrips imbued with Bolts of Bedevilment, Enchanted Embers, Blow Air, Spin Air, Create Flash, Stifle Voice, Open Door, and Summons Spider could actually terrify an ordinary peasant, even though technically all the powers are very low level.